Further to my small scale entry in post 75 (repeated in italics below for completeness) an extensive memory search has concluded I can list the following:
Kerrs Miniature railway (Arbroath)
Isle of Mull Steam Railway
Annat to Corpach Pulp Mill Sidings
Dumberton Central to Dunglass Jn (direct former NB route)
Vicinity of Dunglass junction to Rutherglen (terminal platforms) via Glasgow Central Low level (vicinity of Exhibition Centre to Rutherglen (through platforms) re-opened as Argyle Line
High St to Bridgeton Central
Goods lines High Street to Bellgrove
Airdire to Bathgate prior to closure to freight and lifting
The terminal station at Bathgate provided when Bathgate to Edinburgh re-opened
Dalry to Kilmarnock
Troon avoiding line
Curve off Mauchline line to Hawkhill Jn (Ayr)
Gleneagles to Crieff
Lenzie to Kirkintilloch
Kirkintilloch to Garnqueen South Jn
Lanark to Ponfeigh
The two closed sides of the triangle at Lanark
The closed side of the triangle at Lanark Junction
Larbert to Denny
Larbert to Alloa
Alloa to Dollar
Alloa to Dunfermline (direct)
Old alignment through Forres
Forres to Aviemore (Broomhill to Aviemore no re-opened as heritage railway
Elgin to Keith via Dufftown
Dyce to Fraserbugh
Perth (Bridge of Earn) to Cowdenbeath
Kinnaber Junction to Stanley Junction
Bridge of Dun to Brechin (now re-opened as Heritage line)
Thornton Junction to Leuchars Junction via Leven and St Andrews
Lochty Private Railway
Corstorphine branch
Leith South
Abbeyhill Jn to Piershill Jn via Lochend Jn
Waverley route throughout (part now re-opened but partly on a new alignment)
Longtown Jn to current NR / Mod Boundary (into Longtown MOD)
Carlisle Avoiding Goods Lines
Haltwhistle to Alston (part reopened as Narrow gauge heritage line)
East to south curve at Ashton Moss
Midland mainline from near Swinton to Monk Bretton
New Holland Pier
Kings Cross York Road towards Moorgate (remember 31s into Moorgate!) and return route through the down through platform at Kings X – was it platform 16?
Dover Marine (both routes)
Folkestone Harbour
I would like to add Newhaven Marine but note it is still listed in the SA as ‘Marine Sidings’ – well, I’ve mentioned it anyway!
Maiden Newton to Bridport
Weymouth Quay
Hereford to Grange Court (Gloucester) via Ross-on-Wye
Gloucester Eastgate
Stratford upon Avon to Cheltenham via Broadway (Broadway to Cheltenham Racecourse re-opened as heritage line)
Skelton Jn to Warrington Arpley
Lines closed and re-opened as Metrolink to Altrincham, Bury and Oldham Loop
Previous entry covered in post 75
Fort William old station, Dundee West, Edinburgh Princes Street, Fairlie Pier, Glasgow st Enoch, Glasgow Buchanan Street
Plus walk from Rose Hill to Macclesfield
On an International theme I can add the lines to:
Dun Laoghaire Pier
Dieppe Maritime
Boulogne Maritime
Calais Maritime
Dunkerque Maritime and Dunkerque Ouest
Hook of Holland (subsequently re-opened as Tram/Metro)
Kleve to Nigmegen
Huelva to Ayamonte
Additionally:
Havant-Hayling Island
Portsmouth Harbour platform 2
Brighton platform 9
Eastbourne platform 2
Dumbarton Central platform 4
Helensburgh Central platform 4 (formerly platform 1)
Glasgow Central platform 11A
Gourock platform 4
Largs platforms 3 & 4
Oban platform 2
Stranraer Harbour platform 1
I didn't plan to list closed platforms but will lay claim to all of the Scottish ones except Largs but will add for your local interest
Helensburgh Upper former up loop
Craigendoran former platform 1 (Pier platform - on a different alignment to any of the other 4 platforms there)